The desoxyribosenucleic acid (DNA) content in spermatozoa of fertile and infertile human males

Summary

Microspectrophotometric studies were made on the amounts of DNA in individual spermatozoa of 21 human males with proven fertility and on 18 human males who are partners in sterile couples. The results were as follows:

• 1. The amount of DNA per spermatozoon of the 21 fertile males is very constant and uniform within each individual and among the 21 different individuals. The mean amount of DNA in arbitrary units is 1.22±0.005 per sperm and is approximately one-half that of human somatic cells which is 2.66±0.05.

• 2. In contrast to the uniformity of DNA in the sperms of fertile males, the sperms from the 18 males under examination for “suspected sterility” showed greatly varying amounts of DNA.

• 3. 6 of this suspected group had DNA values close to, but not exceeding that of the fertile males. But for 4 of these 6 males this normal DNA amount conformed to the clinical diagnosis that not the males, but their female partners were responsible for the infertility. The remaining 2 males had sperms with impaired motility, a manifestation which may involve a different factor than that of deviations in the amount of DNA.

• 4. 5 males represented a category of borderline cases in which the mean DNA was slightly lower than that of the normal group, but many individual measurements overlapped those of normal sperms. So far as the clinical diagnosis was concerned, 4 of these 5 males were on the borderline for male fertility while 1 male had been diagnosed as infertile because he had sperms with impaired motility.

• 5. 7 of the suspected group carried sperms with DNA in decidedly lower amounts than those of normal, fertile sperms. In 5 of these 7 males the clinical diagnosis ascribed the infertility to the males. In the remaining 2 cases where the DNA was also found to be low in the spermatozoa, no cause could be given clinically for the sterility either in the male or in the female partner.

• 6. These data suggest a correlation between a deficiency of DNA in the sperms and one type of male sterility, but this cannot be considered as established until further data (such as more information on the female partner) become available.